Is using a 2.5" or 3" Downpipe preferred ?
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Is using a 2.5" or 3" Downpipe preferred ?
Im trying to fabricate my own downpipe for my turbo b18c. For reference, stock block looking to make 350whp no more than 400 in the future. Also I have absolutley no welding experience, but do have a friend with welding experience guiding me. I've already bought all the equipment, just need supplies and practice now. Im running a STC hunter bb turbo w/ a 2.5" outlet. Today I went to measure my existing exhaust piping where the downpipe is going to connect and found out its 2.5", seems to be there's a test pipe where the downpipe will connect. It looks like the rest of my exhaust is 3". So my dilemma is do I just do a full 2.5" down pipe or ditch the test pipe and make the downpipe another 1-1.5' longer?
#2
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re: Is using a 2.5" or 3" Downpipe preferred ?
Ditch the test pipe, do a 2.5" downpipe with a flared section to 3", then include a 3" flex/mesh section somewhere in the DP (possibly the end).
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re: Is using a 2.5" or 3" Downpipe preferred ?
Thanks for the response guys. When looking for flex piping I stumbled across flex bellows, anybody running one of these or have input on them?
https://www.aceraceparts.com/collect...nt=11002653316
I'd like to run a 2.5" elbow first and then flare it to 3" on the way down. Is that going to be restrictive in any way?
https://www.aceraceparts.com/collect...nt=11002653316
I'd like to run a 2.5" elbow first and then flare it to 3" on the way down. Is that going to be restrictive in any way?
#6
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re: Is using a 2.5" or 3" Downpipe preferred ?
Thanks for the response guys. When looking for flex piping I stumbled across flex bellows, anybody running one of these or have input on them?
https://www.aceraceparts.com/collect...nt=11002653316
I'd like to run a 2.5" elbow first and then flare it to 3" on the way down. Is that going to be restrictive in any way?
https://www.aceraceparts.com/collect...nt=11002653316
I'd like to run a 2.5" elbow first and then flare it to 3" on the way down. Is that going to be restrictive in any way?
Can't say anything about the bellows - I've actually been curious about these before as well. I've always just used the woven mesh sections.
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re: Is using a 2.5" or 3" Downpipe preferred ?
It won't be restrictive, if anything it should keep the exit velocity up while still allowing room for expansion immediately afterwards. Should be great.
Can't say anything about the bellows - I've actually been curious about these before as well. I've always just used the woven mesh sections.
Can't say anything about the bellows - I've actually been curious about these before as well. I've always just used the woven mesh sections.
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Re: Is using a 2.5" or 3" Downpipe preferred ?
Pulled the test tube off today, found a number of interesting things.
Where my old down pipe connected, the beginning of the test tube, a whopping 2" ID. I can't imagine how restrictive my exhaust was after going through all of this.
After the test pipe, on the section of the exhaust with the resonator, they welded a reducer to match the test tube.
I also found out I have 2 o2 sensors? The closest one pictured runs into the engine harness, assuming into the ecu and the farthest one is for my afr gauge. Do I need to weld 2 bungs on my downpipe for both of these then or can I get away with just 1 somehow?
Where my old down pipe connected, the beginning of the test tube, a whopping 2" ID. I can't imagine how restrictive my exhaust was after going through all of this.
After the test pipe, on the section of the exhaust with the resonator, they welded a reducer to match the test tube.
I also found out I have 2 o2 sensors? The closest one pictured runs into the engine harness, assuming into the ecu and the farthest one is for my afr gauge. Do I need to weld 2 bungs on my downpipe for both of these then or can I get away with just 1 somehow?
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Re: Is using a 2.5" or 3" Downpipe preferred ?
I ordered 2 bungs just in case. Does placement matter much? Planning on putting the flex bellow at or behind the motor a bit, then an 02 sensor, then maybe another foot or so and the second 02 sensor?
#12
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Re: Is using a 2.5" or 3" Downpipe preferred ?
O2 sensor placement should be pretty much inconsequential for you. I'd just make sure you have easy access to both and that they're angled in a way that provides good clearance around them.
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